In the field of optical search sets many systems exist employing rotating surfaces. In most the surface is planar with a patterned series of apertures therein. By rotating the disc a detector positioned behind the apertures provides outputs definitive of the placement of the source in the field of view. At least one prior system employs mirrors positioned on the inner surface of a wheel with the detector centrally located at the hub.
Disadvantages of all prior systems have been their relatively inefficient use of emission received, and thereby, their relatively limited detection capability. The present invention overcomes these disadvantages by reducing the number of optical surfaces in the path to the detector.